Soil compaction and densification is necessary where soil structure stability is necessary for load bearing capacity. This is especially critical in areas where limestone is present which is notoriously deceptive in its foundation strength especially when water is present. For purposes of example only the soil of South Florida in the United States will be discussed, however, this invention is not limited to the Florida geographical area. South Florida has a soil that includes limestone pinnacles/cavities in combination with sand wherein soil compaction and densification is necessary if the soil is to be used for load bearing purposes. Conventional soil compaction is performed by a deep dynamic compaction (DDC) technique wherein a 20 ton weight is lifted from the ground and allowed to free fall. The weight is lifted by a crane which requires operator skill in positioning during each free fall so that a new position is obtained. However, the free fall occurs from over 100 feet and the ability to hit the exact location is not precise resulting in lost time and higher cost of operation. More critically, should the operator miss the exact mark the soil compaction may fail in that area jeopardizes the foundation footings. Further, the vibration caused by the weigh falling can cause damage to surrounding structures. This becomes critical in high load areas such as airport runways where high static and dynamic loading can occur during airplane landings. Soil compaction needs are necessary around the world; however, the majority of Florida has a unique soil structure of sand and limestone. Well known are the sinks holes that form without notice and are capable of swallowing up a car, house or building. Florida's water table directly affects the soil. Further, the limestone can include pinnacles that must be addressed before any found is placed thereon. Use of a conventional dynamic compaction technique may miss the limestone pinnacles if the impact is not direct. Improper compaction will cause a lack of support and the defect could be concealed during the construction phase, only to cause problems in the future.
Mammoth vibro-tamper (MVT) is a known technology developed and applied in Japan. The MVT technology is a method to compact the surface of sandy ground by using equipment that consists of a strong vibrator and a larger tamping plate. While such a technique works well with sandy soil, a soil that is made of sand and limestone poses a unique situation. Soils that have limestone pinnacles, such as that found in Florida, typically use the dynamic impact process. However, it has been discovered that an adaptation of the MVT to a unique time and combination, provides a method to treat soil conditions having a double layer structure of sand and lime-rock.